On the current version, you can scale up/down an item using the up/down arrow, and rotate it using left/right arrows on your keyboard.
These actions will be soon available in the UI when dragging an item on the floor.
About the height, there is no option at the moment. The height is defined on each module prefab. For floor or ceiling modules it's fine, but for wall lamps or frames it would be great to place them on the wall exactly where we want. Let me know if this is what you are referring to? Unfortunately this is not yet implemented, but I will bump that in my list.